New magnesium alloys with optimized chemical compositions with good biocompatibility were designed. Experimental results show that MZ alloy mainly consists of Ca2Mg5Zn5+α (Mg) and MgZn+MgZn2+Mg2Ca+Zn-Zr compounds. Ca has a strong capability for grain refinement in such alloy. Zr can refine magnesium alloy. Zn addition does not refine the solidification microstructure but plays significant strengthening role during aging treatment. The main strengthening phases of Mg-Zn-Zr alloy are γ(MgZn) and δ(Mg2Zn3). The tensile strength of MZ alloy plate aged at 170°C for 12h is 320MPa, and the elongation-to-failure is 18.4%, the alloy has a potential application of implantation biomaterial.